


Introduction to Real Analysis

by orphan_account



Category: SEVENTEEN (Band)
Genre: Alternate Universe - College/University, Alternate Universe - Professors, Creampie, Desk Sex, M/M, Mathematics, Office Sex, Rimming, Unsafe Sex
Language: English
Status: Completed
Published: 2016-10-30
Updated: 2016-10-30
Packaged: 2018-08-27 06:14:24
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,906
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8390359
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: Thing is, diamonds don't get thrown in the garbage.(Or, a community college professor AU.)





	

**Author's Note:**

  * For [xumyuho](https://archiveofourown.org/users/xumyuho/gifts).



> I'm aware that being a professor is an Official Title but I'm so used to it being thrown around so casually here that I ended up using it—and to distinguish it from a high school teacher and so on.
> 
> There is math and I think that in itself should be a warning.
> 
> Plot is loosely based on Natsume Soseki's Botchan.
> 
> ***
> 
> Aalo, my love, I'm so sorry that I wrote this haha. Even so, there are parts of this I really love, things I never thought I'd write until this exchange happened and I'm really grateful that you were still encouraging me and watering me even though it was supposed to be a secret!!! I honestly have no idea how to write without you anymore haha.
> 
> Anyway, I hope you like it. I love you so, so, so, so much. ♡

**The Triangle Inequality**

 

If a and b are real numbers, then  
| a + b | ≤ |a| + |b|.

 

Myungho twists the bottle of soju open in the stark brightness of his new apartment. It's a little sweet, a lot bracing, and he's reminded a little too much of quiet Chungju outside instead of the obnoxious noise of Seoul, so after that one shot, he screws the bottle shut and puts it away, sighs, rubs his temples with closed eyes.

When he wakes up, he's still in Chungju. An old lady downstairs is dragging along a garbage bag, setting it down for a moment so she can crack her hips before hoisting the bag up into the dumpster. Ramyun for breakfast. Myungho belatedly remembers the egg he cracked open into a bowl for it and adds it into the barely warm soup. The whites coagulate just slightly; the yolk retains rawness.

“Good morning,” his aunt greets him. She has bread and fruit and makes a face at the scent of stale air. The bread and fruit gets put down on the table, nice and pink apples, a shiny, crackly crisp crust on the loaf. It’s picturesque and fitting. “How do you like your new home?”

Boring. Plain. Myungho wants to stab himself with a cookie cutter. “Fine,” he answers. “Do you want breakfast?” She wrinkles her nose just slightly then holds her hand up to decline. There’s a meeting for faculty at the university, and he can either ride with her or ride that sad excuse of a bike his parents dumped him with there.

He opts for a free ride and sits as far away from her as possible, ass barely on the seat. She clicks her tongue but doesn’t snap at him to sit properly, which is good. The university is gloomy, grey even in the morning spring sun. It’s wilting, and Myungho feels sorry for it. The entrance to the administrative building slouches and opens with a creak. Everything else seems to sag. Myungho takes a seat towards the back, entire body dipping down with the chair.

“That one’s broken,” the teacher behind him tells him gruffly before pulling Myungho up by the armpits. Slowly, the chair rises again. Myungho feels his face warm up, yet he stands beside him, clearing his throat. He drags a chair in front of him by its back, but the teacher stops him. “That one’s broken, too.” True enough, when Myungho lets go of the chair, the back of it bends all the way back then slowly rises to about midway before stopping altogether.

Myungho turns his head to face him and ask, “What _isn’t_ broken?”

“Me.”

“Fooled me there.”

The guy snorts and rolls his eyes. “I’m the least tragic thing in this room,” he says with a scoff, “so you could learn a thing or two from me.” He’s well-built, at least. Buff. His biceps stretch the sleeves of his white sweater. 

Myungho rolls his eyes. “Who _are_ you?” he asks.

“I’m Choi Seungcheol. I teach math.”

“Tragic,” Myungho deadpans, but he appreciates the put-togetherness of someone good at math—because he isn’t any better than Seungcheol, not in the least. His aunt is starting to talk, starting off with thanking them for their hard work the previous school year, how she hopes it will continue for this year. Have they all submitted their proposed syllabi for the semester? Friendly reminder that it’s due the weekend before school starts again.

“Do you teach literature?” Seungcheol asks, his voice now dropped to a low murmur.

“No.”

“Philosophy.”

“Fuck no,” Myungho shoots down. “I’m teaching Chinese.”

Seungcheol laughs hard at that, enough for the nearest teacher to look back with a glare. “Get this, Jeonghan,” he tells the teacher, “he’s a Chinese teacher.”

“Funny, kid,” Jeonghan says with a laugh of his own, “we don’t teach Chinese here.”

“With you here, we might as well not teach physics either,” Seungcheol deadpans, making Jeonghan frown.

“Ya, Cheol-ah, I didn’t vote for you so you could insult me like this.”

“Is everyone here a shitty teacher?” Myungho asks, his voice cracking a little in disbelief.

“Yeah, pretty much,” Seungcheol agrees after a shared look with Jeonghan. “I mean, there’s Hannie and Mingyu… Seokmin gives too many As—”

“We almost fired Seungkwan last year for failing too many students,” Jeonghan adds as he tucks a lock of hair behind his ear. “You’ll fit right in.” 

Myungho’s afraid of that, really. He doesn’t realise that the meeting has finished and the sad faculty have all gotten up from their chairs to amble to the sides of the room for coffee from a thermos and pastries from the supermarket until Jeonghan gets up and invites him to his and Seungcheol’s place.

“You want shitty coffee or shitty booze?” Seungcheol asks when Myungho hesitates.

“Booze.”

 

 

 

**The Archimedean Property**

 

If p and ε are positive numbers, then there exists an integer n such that  
nε > p.

 

“You can’t be fucking serious.” Seungcheol doubles over laughing just as his legs extend to kick Jeonghan’s thigh.

“That sounds like something the president would do,” Jeonghan muses. He sets down his mug of soju and makes grabby hands at Myungho. “Come here, Myungho-ya.”

Myungho eyes the hands warily and doesn’t set down his own mug, now half-empty of soju. “Why?”

Jeonghan answers, “I need to know what being rich feels like.” He shakes his legs and pouts at Myungho.

“Date him, then,” Seungcheol suggests to Jeonghan as he meets Myungho’s eyes when Myungho gets up from his seat—rather, the floor—and walks over to Jeonghan, who immediately plays with the fabric of Myungho’s shirt between his fingers.

“No,” Jeonghan whines. “He’s not rich _now_ , but, fuck, feel his shirt! It’s so soft, but it’s, like, _substantial_ —” He checks the tag. “Hand-wash only? Well, fuck me.”

“I had maids…” Myungho mumbles. Seungcheol beckons him to come nearer, his fingers warm when he runs his hands down Myungho’s sides.

“Maids,” Seungcheol repeats with a snort. “How’s that feel? Cushy?” His fingers tingle, and Myungho misses them when Seungcheol withdraws from his body. “Well, shit.”

Myungho remains standing in front of them and the soju tastes a little cheaper inside his mouth. “What?” he demands. “Gonna shit on me for it?”

Seungcheol laughs. “Not at all. I just think you’re stupid for being a fuck-up.”

Jeonghan frowns and reaches for Myungho again, pulling him onto his lap. “Cheol-ah, you’re being harsh,” he admonishes, then asks Myungho if his perfume is from Jo Malone. This close up, Jeonghan reeks and slurs. “Don’t worry about it, Myungho-ya. I’m a fuck-up, too.”

Myungho’s afraid of that. He turns his head to see Seungcheol’s mouth turned down into a scowl.

“Hey, don’t encourage him,” Seungcheol scolds Jeonghan. “The president brought him here for a reason.”

“Don’t tell me you side with the president?” Jeonghan asks, incredulity colouring his voice.

“I’m not,” Seungcheol grumbles.

“You really shouldn’t,” Jeonghan says. “You know she made that dating ban because of you.” Myungho snorts and steals a sip of soju from Jeonghan’s mug, settling himself nicely on Jeonghan’s lap, who doesn’t seem to mind and even wraps his arms around Myungho’s waist with overwhelming tenderness. 

Seungcheol leans his head back further into the couch and heaves a heavy sigh. “Don’t remind me, fuck,” he says. “She caught me right when Soojung was taking off her panties. How the fuck was I going to give a mathematical explanation for that one?”

 

 

 

**The Order Relation**

 

For each pair of numbers a and b, exactly one of the following is true:  
a = b, a < b, or a > b.

 

Myungho sets down his box of things into a cubicle which the air conditioning has made its main target. The hairs on the back of his neck stand up in the chill, the wind biting down on his knuckles. A teacher comes by to drop a folder on his desk, some of the sheets of paper spilling out of it when it lands.

“Class schedule,” the teacher explains. “Looks like you only have nine units.”

“Better than zero,” Myungho replies with a shrug. “How about you?”

The teacher grins widely. “Full load,” he says then bites into the apple in his hands, juice spraying everywhere from his lips, “so that's eighteen units plus I’m acting head.” Good for him. Maybe he wants Myungho to pat him on the back.

“Congrats.”

“I don’t need it from you,” the teacher says lightly, “but thank you anyway.” Myungho looks at the apple, now with a huge bite taken from it, and wonders how appropriate it would be to choke the social sciences department’s acting head with it.

“Shut up,” another one says with a large scowl. He leans his wrist on the wall separating Myungho’s cubicle from the other’s and lets his fingers dangle in front of Myungho’s face. “Everyone’s required to take your classes, Soonyoung.”

“Aw, Seungkwanie,” Soonyoung says as he leans forward and pinches Seungkwan’s cheek with fingers sticky with the apple’s juices, “you don’t have to be jealous. Acting head could’ve gone to anyone.”

“They picked you because you have less work to do,” Seungkwan snaps, “unlike I, whose classes _matter_ —”

Myungho eyes the stapler he’s unpacked and placed on his desk and consider’s Soonyoung’s lips, which are flabby and can so easily be stapled if Myungho tried, and Seungkwan’s lips, which are nonexistent but Myungho’s willing to try his hardest. When he looks back up, another teacher has started to settle into his own cubicle across from Myungho, feet promptly placed on the desk.

“Have you both forgotten what happened last school year?” that teacher says. He fishes a box of cigarettes from his coat pocket and taps it on his desk.

“No smoking in campus, Jihoon,” Soonyoung admonishes.

“Fuck off,” Jihoon scoffs. “You got that position because of me, remember? _I_ turned it down and _you_ were the only ass-kisser—What, you disagree with me?” He clicks his tongue when Soonyoung makes a face at him.

“You make me sound horrible in front of the new teacher,” Soonyoung complains.

Jihoon snorts. “He deserves to know. Myungho, was it? Just know that Kwon Soonyoung has entitlement issues—” He stuffs the cigarette between his lips and lights, cursing with smoke curling out of his mouth when the bell rings. Everyone else is leaving, taking along with them planners and folders. Seungkwan stops in front of Jihoon's desk again before heading out.

“You’re not going to your first class?” Seungkwan asks.

“I don’t have one right now,” Myungho says.

“Not you, dumbass,” Seungkwan cuts off. “Jihoonie.”

“Fifteen-minute allowance,” Jihoon sighs as he leans back into his chair. “I’ll go when I finish this.” Myungho debates on asking him for a cig, but Jihoon doesn’t look like the type to share; he finishes his cigarette in quick puffs, stamps it out on the sole of his shoe, then gets up, barely paying attention to Myungho as he walks past him.

The sudden silence, the whirr of the air conditioners take Myungho aback, and he has to stand up to peek over the cubicles and see who else are left. He meets the eyes of someone on the other side of the room precisely because that guy was also peering over the cubicles, his arms folded over the edge of his own.

“Yo,” the teacher greets.

“Yo.”

“Did Soonyoung leave already? I haven’t submitted my syllabi yet.”

Fuck. “Fuck,” Myungho says blandly. The teacher laughs then smiles, all teeth, sharp canines.

“You forgot? What time's your first class?”

“Eleven.”

The teacher slips out of his cubicle and makes his way to Myungho, towering over him in his gangliness. “Let's get coffee,” he suggests. “There's a PC-bang somewhere here with coffee.”

“What—”

“Come on, I’ll help you finish your syllabi.” He smiles while Myungho stares at him, wondering what exact kind of idiot he is. “I’m Mingyu, by the way,” he says with an extension of his hand that Myungho warily takes, letting himself get led out of the cubicle.

“Seungcheol said you’re a shitty teacher,” Myungho offers after he’s put himself together, slung the bag over his shoulders. Mingyu laughs and shrugs. “Is it true?”

“Does it matter?” Mingyu counters. Myungho laughs, and the taste of it feels odd in his mouth.

 

 

 

**The Completeness Axiom**

 

If a nonempty set of real numbers is bounded above, then it has a unique supremum.  
(Similarly, if a nonempty set of real numbers is bounded below, then it has a unique infimum.)

 

“The hell should I put under ‘learning objectives’?” Myungho asks. Mingyu’s eyebrows knit together, the game on the PC reflecting off the high points of his face, and he leans into Myungho’s space to read what Myungho’s typed on the screen.

“You know,” Mingyu starts, though Myungho doesn’t really know, “what you want your students to learn from you. Chinese, right? So they should be able to communicate basic personal information in Chinese at least. Understand and appreciate the richness and vibrancy of Chinese culture through its language. Shit like that.”

“One more,” Myungho says as he types it out into the document, muttering to himself as he tries to remember the exact words Mingyu’s just said. “How about the student being able to relate Chinese culture to Korean?”

Mingyu barks out a laugh and it surprises the guy on the computer to his right. “Honey,” he says with a sigh, “everyone knows how they relate.”

“Does it matter?” Does he care?

“Whatever, man. Just get that shit printed,” Mingyu urges. He finishes his iced coffee and resumes his game, cursing when he gets set back, so he throws himself back on the chair in frustration and turns his head to look at Myungho, who’s playing with his mouth, taking his bottom lip into his mouth and chewing it in frustration. “Where are you stuck?”

“I have no idea what I’m fucking doing,” Myungho admits. The syllabus form is all filled out except for grade composition and classroom policies, but Myungho has the urge to start everything over and he watches the cursor on the word processor blink in and out of existence, his fingers curling into the keyboard.

Mingyu lets out a sigh then looks into Myungho’s screen again. “It looks fine,” he says. “What the fuck are you so worried about? Soonyoungie rejecting it? _Soonyoung_?”

Myungho brushes Mingyu off with, “Just gotta do a good job,” that Mingyu snorts at.

“Come on,” Mingyu whines, “you’re gonna make me and the rest of us look bad.” Myungho doesn’t really see what’s so wrong about that, so he scrolls back up to the first page of the syllabus for his introduction to Mandarin class and rereads.

But syllabus or not, Myungho realises it doesn’t matter. His students don’t know a thing and prepare their stuff ten minutes before class ends. Over a lunch of rice and kimchi jjigae in a thermos, Mingyu says it’s okay and it happens to everyone. Over soju and ramyun with cheese slices on top, Jeonghan says it’s not a big deal and Seungcheol calls Myungho out for acting like he’s never done that when he was in school.

His aunt comes into his cubicle one Thursday afternoon to check up on him, finds him curled over ancient Chinese calligraphy while Jihoon quickly stamps out his cigarette with the sole of his shoe, but the air still smells like smoke and it makes her cough into her pristinely steamed blazer. Soonyoung comes in and loudly admonishes Myungho for smoking.

“Should I tell you about Kwon Soonyoung?” Seungcheol prompts one evening.

Jeonghan has to supervise a night class’ lab activity, help students fix their coding so the robots could work, but they get it anyway, so all Jeonghan has to do is sit down and check problem sets of his own students. Myungho has been stuck on the same lesson all week and it’s driving him up the wall to watch Wonwoo, a history professor, photocopy page after page from his stack of textbooks. Just a little. (But what pisses Myungho off more is Wonwoo pretending he doesn’t exist when he offers to help with carrying all that material back to Wonwoo’s cubicle.)

“I don’t want to think about him,” Myungho grumbles.

“Fine, then do you want to help me check this? I have an answer key,” Seungcheol asks. “It’s simple calculus.”

“‘ _Simple_ ’,” Myungho mocks. “Fuck that. Tell me about Soonyoung.” Seungcheol motions for him to come closer, pulling Myungho on his lap as soon as Myungho was near enough then wrapping his arms around Myungho’s waist.

“You’re taller than me,” Seungcheol complains after trying to place his chin on Myungho’s shoulder.

“Yeah.”

“What the fuck. Lower your head.” Myungho does as he’s told then Seungcheol says, “Soonyoung is trying to be the official head of social sciences. But thing is, Seungkwan is also trying.”

“So?” The sides of Myungho’s mouth curl up when he sees a solution on one of the exams boxed in red with the words _Do you really think this is right?_ Another with the whole thing covered in a large red question mark. It’s almost hard to believe Choi Seungcheol sleeps with his students. Almost. 

“It’ll be fun, right?” Seungcheol says with a laugh. “Do you like Seungkwan?”

“Not really,” Myungho deadpans. “So what was that thing about Soonyoung?” He leans back to rest his head against Seungcheol’s shoulder, prompting Seungcheol to reach for Myungho’s hand and play with his fingers. “Hello?”

“I don’t know…” Seungheol admits. “He’s kinda boring, isn’t he? It’s something you already know.” At that, Myungho slumps further back into Seungcheol and whines.

“Hyung…”

“It was pointless, I know.”

“I’m on your lap.”

“I wanted you here.”

“Then work like this,” Myungho challenges.

“Fine. Give me my papers.”

Myungho obliges, handing Seungcheol back his stack of papers and his red pen then settles into Seungcheol’s lap like he was born to sit there. He watches Seungcheol completely ignore the answer key and follow the solutions with his head, the entire stack perched on the arm chair. “You take your job seriously,” Myungho remarks.

Seungcheol snorts. “I do,” he says. “I should.” One of the items gets full credit. It’s far from neat, but it’s right.

“Then why students?”

“Why not?”

“You could get anybody.”

“Wouldn’t that include students?”

“You know what I fucking mean.”

“Why don't you ask Mingyu to psychoanalyse me?” Seungcheol asks. “He could tell me it's childhood trauma and you'll believe him and pity me.”

Myungho turns his head to face Seungcheol, whose forehead only comically reaches Myungho's shoulder in this position. “Then what? I'll let you fuck me?”

“If you don't want to, just say so.”

“You could do better,” Myungho tells him after a long swallow. A lot better. One who maybe understands what a derivative is. Or at least a teacher who knows what’s happening in his own class, but Seungcheol bursts out laughing.

His laugh is long and loud, nose bumping into Myungho’s back. “Believe me, I know that, but being here makes me wonder if that’s still true.”

 

 

 

 

**Interior Points**

 

Let S be a set of real numbers. A point x o  is an interior point of S if there exists an ε-neighbourhood of x o  that is entirely contained in S.

 

This is what Myungho finds out about Seungcheol: he rejects a job in Seoul following the death of perhaps the most esteemed member of faculty in the university—a doctor of mathematics and Seungcheol’s thesis adviser. Seungcheol feels like he can’t leave. Myungho, a lanky thing on Seungcheol’s lap, finds it the funniest thing on Earth.

“You know a chaebol like you doesn’t get it, right?” Seungcheol grumbles not unkindly.

“It’s just…” If Myungho sees another iteration of Seungcheol underlining a statement in the exam and trailing question mark after question mark beside it, he will lose his shit. “You’re so pathetic. Look at you. You hate this job.”

“So?”

“Shouldn’t you be happier?”

Seungcheol snorts. “Aren’t you just waiting for mommy and daddy to welcome you back?” he retorts. “Save you from this country bumpkin life?” Myungho finds himself in the awkward position of not knowing if he should slide off Seungcheol’s lap or not, if he should move the heavy arm Seungcheol’s wrapped around his waist. “Don’t tell anyone, okay?”

“That you hate this job?”

“Of course.” Seungcheol covers Myungho’s arm with his own, lacing the backs of Myungho’s fingers in his. “My job is on the line.”

“This shitty job.”

“Yeah.”

“That you hate.”

“Yes.”

It makes Myungho squirm to get off Seungcheol’s lap, falling instead to Seungcheol’s side, where they can look at each other properly. Seungcheol finally looks like he’s tired, the bags, the way his mouth refuses to set, and Myungho just rolls his eyes at it.

“Whatever, it’s your life,” Myungho drawls. He stretches himself onto the couch, sprawling his limbs everywhere they can reach. “I’m gonna try enjoying mine.”

Seungcheol snorts. “Good luck with that.”

 

 

 

**Limit Points**

 

Let S be a set of real numbers. A point x o  is a limit point of S if every ε-neighbourhood of x o contains a point in S that is not possibly x o  itself.

 

Mingyu comes into Myungho's cubicle with a feral laugh. “You gotta see this,” he says, and he means Seungkwan and Soonyoung bitch fighting outside the department like an old married couple. Myungho lets himself get dragged outside.

“You could at least _do your job_ , Kwon Soonyoung,” Seungkwan snaps.

“Soonyoung asked Seungkwan to cover for him at a meeting,” Mingyu explains in a whisper. They’re not the only ones watching; Jihoon is watching disinterestedly, probably waiting for the bell to jolt him and drag his ass to his next class.

Myungho likes how all this is spectacle.

“It’s just this one time, Seungkwanie,” Soonyoung says lightly. “After all, you’re not all that busy—”

Seungkwan nearly squawks, demanding, “What _even_ gave you that impression?” His face is colouring a nice red in the light of the setting sun, and Myungho is beginning to feel sorry for him, how he looks tiny in the face of a huge asshole like Soonyoung. But Myungho ends up shrugging it off and heading back to his cubicle to correct his students’ hanja while Mingyu pipes up and tells Soonyoung to knock it off.

Some time later, a little after nightfall has broken out and Myungho is halfway through his stack of papers, Seungkwan comes back and plops himself loudly down on his chair in his own cubicle.

“I’m gonna get that asshole fired,” Seungkwan complains. From his cubicle, Myungho can imagine Seungkwan rubbing his eyes with clenched fists, maybe leaning back on his chair because he doesn’t want to do anything else with his hands. “Or I’ll get myself pirated away by a better university…”

Wonwoo speaks up, his deep voice filling up the room, “Are you sure they’ll get you?”

“They _have to_ ,” Seungkwan grouses. “I can’t stand another fucking semester with Soonyoung. I don’t see how anyone else doesn’t notice how he’s a lazy brown-noser, or, like, people do, but no one is doing anything about it. I mean, I know you and Jihoon are okay with him, but there’s definitely someone who doesn’t want him around, right?”

“I do,” Myungho says while standing up, restacking his papers to bring home to correct. Seungkwan looks up at him from his cubicle, his intial shock quickly turning into a frown.

“Oh.” Seungkwan clears his throat. “I thought you went home already.”

 

 

 

**Boundary Points**

 

Let S be a set of real numbers. A point x o  is a boundary point of S if every ε-neighbourhood of x o  contains a point in S and a point in S C .

 

The door to Seungcheol’s home is unlocked, and somehow Myungho feels it’s always been that way, like neither Seungcheol nor Jeonghan have things precious enough for them to keep their door locked. (Honestly, if Myungho got robbed right now, he would cry, but only because he splurged last month’s salary on booze he finds palatable.)

No one is in the living room, but there are clothes scattered on the floor.

“Oh, hey, Seungcheol’s not home,” Jeonghan says, making Myungho jump. He only has a shirt on, boxers as well, and he pads into the kitchen for a glass of water. “Unless you’re here for me?”

“It looks like someone’s here for you, though,” Myungho retorts. There’s a blooming hickey on Jeonghan’s neck, on the side below his ear. 

“Hey, Hannie, I want one, too,” Soonyoung says as his body pops out of the doorframe leading to Jeonghan’s bedroom. He’s ass-naked, and Myungho kind of hates himself at this moment. “Oh.”

 

 

 

**Isolated Points**

 

Let S be a set of real numbers. A point x o  is an isolated point of S if there exists an ε-neighbourhood of x o  that is entirely contained in S C .

 

Mingyu gets fired, but he doesn’t protest. Rather, he gets a little gleeful and promises Myungho a round on him next time they see each other.

 

 

 

**The Existence of the Integral**

 

If _f_ is bounded on [a, b], the lower integral is equal to the upper integral, and both are equal to L, then  
the proper (Riemann) integral exists and is also equal to L.

 

“He was gonna bring me sightseeing,” Myungho grumbles into his whiskey glass. His fingers feel numb against it, like it could fall and shatter into the floor at any moment and he wouldn’t feel it slip through his fingers. Seungcheol’s feet are propped up on his desk, which is deceptively clean (the papers were all left as piles in boxes on the floor near the door, tucked into darkness so Seungcheol doesn’t have to look at them while nursing his own glass of whiskey, which was slowly getting watered down from melted ice as he waits for Myungho to stop complaining about Mingyu’s absence).

“Where do you think he went?” Seungcheol wonders aloud. “Can’t be any worse than this place, can it?”

Myungho tilts his head back and stares at the ceiling. “I might side with Seungkwan now,” he admits.

Seungcheol snorts and takes a long sip of his drink, exhaling with a satisfied sigh. “That’s what I’ve been saying,” he says. “Besides, I don’t want to deal with Soonyoung anymore. He keeps trying to butter up Hannie.”

“I really liked Mingyu,” Myungho whines, trying to place the thought of Soonyoung and Jeonghan fucking somewhere equivalent to the under-the-rug of his memory.

“More than me?” Seungcheol asks.

“Would you be hurt if I said yes?”

“Well, obviously.”

“Then no, I like you more,” Myungho says, letting out a loud laugh when Seungcheol huffs. “What’s with you, huh?”

“What?” Seungcheol demands. He lets Myungho get up from his chair and sit on his lap, catching Myungho by placing firm hands on the small of his back. “What?” he says again, breaking into a grin when Myungho loops his arms around him.

“You’re like… more miserable this week.”

“Ex is in town,” Seungcheol says in a low voice. “We were supposed to get married.”

Myungho’s breath is forced out of his lips when Seungcheol drags him closer. “What happened?” he asks and he cringes at how it comes out in a squeak.

“I took this fucking job here, she got a job in Busan…” Seungcheol slurs, and this close, he just reeks of whiskey, of the five glasses he’s had since Myungho dropped by his office. The moonlight filters through the window, highlighting the slope of Seungcheol’s nose that Myungho wants to trace with his fingers. “The thing is, I’m not mad at her.”

Myungho hums. “Why?”

“If I were her, I would’ve done the same thing.”

“Do you miss her?” Minghao asks.

“Does it matter?” Seungcheol counters. “We were college sweethearts or something. Fucked in unused classrooms a lot. She always liked taking charge and I sat back and watched her…” Skirt pushed up and over her ass, bent on the desk, Seungcheol rutting into her until he comes… Or, she grinds into his thigh and he pushes up to meet her every time she comes down. Seungcheol’s eyes narrow as he looks at Myungho. “What are you thinking?”

“You,” Minghao answers, “fucking her.” His insides feel flush with heat. Seungcheol, who laughs, feels so sturdy and solid underneath him, and maybe that’s why she felt like she could take charge—

“We can,” Seungcheol says. “I don’t mind.”

“Not minding isn’t wanting,” Myungho says, but he just wants to shut up for once, to kiss Seungcheol while he’s still pliant and open like this.

Seungcheol traces a light finger down Myungho’s throat, feeling Myungho gulp beneath the tip. “I want you,” he says in a low voice, “if that wasn’t obvious.” With the same hand, he curls his fingers into the back of Myungho’s neck and brings him down to kiss him, taking Myungho by surprise, his mouth slack against Seungcheol’s until he remembers to move it.

And Myungho’s never kissed someone who kisses like it’s all he wants to do, like he has nothing to prove. He presses himself even more flush against Seungcheol’s body, tightening the loop of his arms around Seungcheol’s shoulders. He rolls his hips into Seungcheol’s lap, letting Seungcheol’s groan ring in his ears. When he lets go, Seungcheol follows, blindly trying to chase Myungho’s mouth with his own until he finds it again or until he latches on to the sensitive skin of Myungho’s throat, sucking on it till it breaks then laps on it with a warm and rough tongue.

It makes Myungho hyperaware of just where Seungcheol’s mouth is, the bit of hot air when Seungcheol exhales, the hiss when Myungho grinds down again on his lap and the press of cold teeth against Myungho’s skin. Seungcheol finds Myungho’s lips again and sucks on the bottom one, breaking out into a grin when Myungho lets out his choked version of a moan, one that loses control the moment it leaves his mouth.

“Fuck,” Seungcheol exhales. His hands slip underneath Myungho’s shirt to lift it up and off, and they’re now too warm—almost searing—on Myungho’s skin.

Myungho hisses at the contact, takes his bottom lip in his mouth and chews on it, body arching towards the hand Seungcheol has hovering over his collarbone, towards Seungcheol’s mouth that’s acquainting itself with the surface of Myungho’s body. He tangles his fingers in Seungcheol’s hair—it’s soft, with a pervading greasiness at the roots that makes Myungho stop and graze his nails on the scalp again and again. Seungcheol sighs against Myungho’s nipple, the breath of hot air making Myungho shiver.

He feels nails raking the expanse of his back, and Myungho likes to imagine that Seungcheol’s stubby nails are enough to make it happen, heat spreading over his skin. Seungcheol tugs on the waistband of Myungho’s trousers, moving forward to the button of them so he could work it free and tug the trousers down to Myungho’s thighs with little resistance. Once Myungho’s bare ass meets the rough denim of Seungcheol’s jeans, Myungho finds himself lifted and placed on the desk, back flush against the surface, legs in the air and knees tucked close to his chest.

Seungcheol drags Myungho’s trousers all the way down then discards them by the foot of his chair, sits back down, and spreads Myungho’s legs, tucking his face into the crook to press the flat of his tongue against Myungho’s hole before bringing his head back up to leave wet kisses along the underside of Myungho’s thighs.

The ceiling is drab grey, Myungho knows and has noted down before, but it’s cast blue now; the streetlights etch the windows onto the surface in a wash of white. He tries to find his fingers and they catch on Seungcheol’s glass, bringing it down to the floor, where it spills whiskey into the carpet. Seungcheol has his arms hooked around Myungho’s thighs, swallowing them in their bulk and pulling him in closer, the sounds coming from his tongue slick and wet.

He’s warm. He groans around Myungho’s entrance like he’s getting filled up though there’s nothing for Seungcheol to bunch up in his hands.

“You know,” Seungcheol pulls away to say, “I like hearing you like that.”

Myungho cranes his neck to look at him, at his hair plastered down the sides of his face and forehead from sweat, at his shiny, swollen lips, and he licks his own. “Like what?”

“Like… a caged animal.”

“Sexy,” Myungho notes drily, but he gasps when Seungcheol nibbles on his thigh, kisses his perineum.

“Like that,” Seungcheol says. He draws out each new lick until Myungho tangles his fingers into his hair, matted down with sweat, and _pulls_. Myungho presses himself against him, back arching off the desk.

It’s a little embarrassing when Myungho comes, white streaks of it landing on his stomach, a strangled noise leaving his lips; he barely touched himself when he starts quivering around Seungcheol’s head. Seungcheol watches with his eyes hooded over, tongue slowly tracing the curve of his bottom lip. He traces circles with his palms into Myungho’s hips, pressing himself between his legs.

“Is it too late for me to fuck you?” Seungcheol asks. He takes off his shirt without much fanfare and wipes the come off Myungho’s stomach with it, tossing it to the side while Myungho breathes out a laugh underneath him.

“Whatever. _Wreck me_ , Choi Seungcheol,” Myungho says, then reaches up to steal a quick kiss from Seungcheol, who was bending over him so their stomachs were flushed against one another, and grins back when Seungcheol lets him steal another.

Seungcheol pulls back so he could get condoms and lube from a drawer in his desk, and from the rattle, Myungho knows there is _a lot_ , but he doesn’t pay it any more mind when Seungcheol presses the tip of a lube-slicked finger against his entrance and rubs circles all over it with steady pressure that makes Myungho writhe.

“You sure?” Seungcheol asks. 

“Yeah.” There’s the stretch, the slight burn. Seungcheol inches his way into Myungho, one knuckle joint at a time, but Myungho hisses anyway, mouth falling open and staying that way. “I need more,” Myungho says when he finds it in him to move his mouth.

“More what?”

“ _Lube_. It hurts.”

Seungcheol laughs and pulls out, obliging Myungho by drizzling lube on his fingers until they’re shiny and wet, slipping in with the wettest imaginable sound. It makes Myungho’s stomach curl into a tight knot. It makes him want to cling on to Seungcheol’s shoulders. “Better?” Seungcheol then asks.

“Fuck—” If Myungho closes his eyes, it’s all he could feel; he’s the asshole Seungcheol’s inserting one, two fingers in. When Myungho closes his eyes, he lets out a strangled laugh then chokes on it, his fingers trying to find purchase on the smooth, enameled surface to curl into (they keep slipping because Myungho’s hands are clammy, sweaty things).

At one point, Seungcheol stops to put a condom on, and Myungho can feel his mouth curling and moving to tell him to not use it. He wants to feel that warmth literally pool inside him. Seungcheol takes Myungho’s ankles and places one on each shoulder then brings down his jeans to his knees along with his underwear, the belt jingling on its way down.

“What’s with you, huh?” Seungcheol asks.

“What?”

“You’re really gonna let me do this?”

“Not that I’m letting you,” Myungho slurs out. “I _need_ you to do it. Or, like, I want you to. Fuck, hyung, just do it.”

“Watch your fucking manners,” Seungcheol counters, but he pulls Myungho closer to him once more, aligns himself, then pushes into him, quickly fixing his pace into something rushed, hasty, rough. Myungho’s back chafes against the table. The backs of his thighs are red with heat.

Seungcheol reaches forward to grip his shoulders hard, his thumbs digging in. They’ll leave bruises, but Myungho’s just glad his scapula won’t break under the pressure, from Seungcheol tightening his hold to make sure he doesn’t slip as he thrusts hard into him. A long, low groan comes out of Seungcheol when he comes, when he spills warmth inside of Myungho and lets him feel full a second time.

He doesn’t pull out right away but instead lingers and turns tender. He kisses Myungho’s forehead and pats his head, making Myungho whimper under his touch. “Shit,” Seungcheol says when he finally pulls out, eyes fixated on Myungho’s entrance, which was leaking come unto the table (Myungho can feel it every time he breathes, a little of Seungcheol’s come dripping out of his body, and it’s strange yet so annoyingly satisfying, especially the look in Seungcheol’s eyes and the way he takes in his bottom lip to chew on as he determines what he wants Myungho to do next). “Touch yourself,” Seungcheol instructs after he helps scoot Myungho further up the desk so Myungho could plant his feet flat on top, his knees spread open.

It’s only then that Myungho remembers his own neglected cock, achingly hard and an angry red. He reaches down to jack himself off and finds it strange how his fingers refuse to curl, but they have to, now that Seungcheol is watching him in the glow of the moon and streetlights with his eyes surprisingly clear and sharp. Seungcheol hovers over Myungho, hands on either knee.

Myungho lets out a moan—the hurried, short, almost gasps kind that makes Seungcheol’s mouth open. He arches up, eagerly trying to fuck his fist. He breaks into whimpers, bites his lip so hard he can taste metal as blood stains his tongue when he darts it out to lick at the wound. At that, Seungcheol curls his fingers into Myungho’s knees, almost clawlike in their grip, and meets Myungho’s eyes, staring him down until he comes. Then he reaches down a hand to help jack him off, come running down his knuckles.

(Perhaps the most satisfying thing is seeing Choi Seungcheol lift his knuckles to his mouth and lick the come away from it until his hand is clean and shiny with spit.)

Myungho’s head lolls back dangerously over the edge and he lets it, watching the world around him tilt upside down. The warmth of Seungcheol’s body is completely gone and is instead replaced by the clinking of Seungcheol’s belt buckle as he pulls his jeans back up. He walks to one of the shelves and comes out with a clean t-shirt. Myungho can’t read it from where he’s looking, but it’s in the school colours, a little too tight for Seungcheol when he puts it on that Myungho forgets that his ass, entrance and all, is bared to the large, curtainless window.

 

 

 

**Continuity**

 

Differentiability implies continuity implies integrability.

 

It turns out Soonyoung can never fire Myungho, not without earning the ire of Myungho’s aunt, at least, but Myungho still sends a few letters out and waits for a call that comes when he’s in Seungcheol’s home, sprawled on the couch with his head on Seungcheol’s lap.

“What’s that about?” Seungcheol asks gruffly the moment Myungho hangs up. There’s nothing on TV of note; it’s on mute and Seungcheol’s nursing what is probably his fourth cup of coffee for the day, his other hand absentmindedly stroking Myungho’s hair in a manner that passes for domesticity.

“I have an interview,” Myungho explains. With a dry laugh, he adds, “I almost forgot I could speak Chinese. I applied to a bank where I can work with Chinese clints.”

“So you’re going to China?”

“Just to Seoul.”

Seungcheol nods. “I’ll go with you,” he says. “To your interview.”

Myungho could kiss him, but that involves getting up. “You’re gonna submit a resumé, too, aren’t you?” he teases.

“I might,” Seungcheol says quietly. “You’re right; I’m miserable and I hate this job. Besides, one of my graduating students is teaching next year.”

“You have a masters in math,” Myungho says blankly.

“So?”

“It’s a huge loss for the school.”

Seungcheol sighs. “I’ll still go with you. When is it?”

“This weekend.”

“Help me pack? Get up.”

Myungho does and follows Seungcheol to the room, where Seungcheol quickly puts out a small luggage then ducks into the bathroom, leaving Myungho to pack Seungcheol’s underwear, a plain shirt. The feeling is odd but makes Myungho smile a little, and he folds the clothes into the luggage with care.

Seungcheol comes back in a suit with the shirt untucked, and Myungho laughs. He tucks the shirt in and buttons it up, fixes the lapels of Seungcheol’s blazer. “Do I look okay?” Myungho laughs at that.

“Now you do.” With Myungho’s thumbs hooked into the waist of Seungcheol’s trousers, he pulls him closer. “Nervous?” He’s never seen Seungcheol shy or flustered, but it’s coming out now, how Seungcheol’s eyes crinkle when he smiles, his loose laugh. How the suit doesn’t fit him so well but he tried.

“What can I say? I’m just a country bumpkin.”

“You know… If I don’t get the job, I don’t mind staying here,” Myungho admits with an easy smile. “Fuck Soonyoung.” More like he’ll find a way to get that asshole fired, but whatever.

Seungcheol laughs and tilts his head up to kiss Myungho. “You’re a good kid, Seo Myungho,” he says, and Myungho thinks he can believe it.

**Author's Note:**

> An ε-neighbourhood is essentially the interval (x-ε, x+ε). If you guys are unsure of anything, please don't hesitate to ask!! The snippets are meant to relate to the text in some way, and I'm not sure if that was apparent.
> 
> It's my first time writing something Minghao-centric and it only occurred to me that I've never written him as more than a side character so I'm kinda nervous haha please be kind ;; I'll definitely try to write better in the future~


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